In wireless communication systems, low noise performance, high gain, high linearity, low power consumption and small area consumption of the semiconductor devices is desirable or required. In particular, in mobile telecommunication devices, as for example mobile handsets or the like, low power consumption and small area may be of importance since the devices or mobile phones are powered by batteries. Moreover, in a wireless receiver, the first amplifier within an amplifier chain may be required to generate as little noise as possible, at the same time providing a high gain to enable a low noise figure of the whole amplifier chain.
A cascoded common source amplifier is often used as a first amplification stage, which is essentially composed of two transistors in series, the first being operated in common source mode and the second being operated in common gate mode. The cascoded common source amplifier is also called cascode circuit herein. A cascode circuit may provide for an output voltage which is amplified with respect to the voltage input into the amplifier circuit. An amplifier stage may provide a voltage output or current output depending on the loading of the following stage.
In some applications, an output of an amplifier stage should be capable of driving subsequent mixers used to down-mix or down-convert a received radio frequency signal into a baseband signal. To this end, transconductance amplifiers may be used, which may also be seen as a voltage controlled current source. A transconductance amplifier may, for example, comprise two transistors connected in series, the transistors being made in complementary technology. That is, one transistor may be a PMOS-field effect transistor (FET), while the other transistor may be a NMOS-FET.
In order to provide considerable gain within an amplifier chain as well as desirable output characteristics, different amplifier types are sometimes connected in series or cascaded, the individual amplifiers requiring individual power supplies and biasing circuitry as well as a considerable amount of semiconductor area, which may be undesirable.